Logan et al U.S. patent application Ser. No. 043,394 filed May 25, 1979, now abandoned in favor of U.S. Pat. Ser. No. 134,029 filed Mar. 26, 1980, discloses the fractionation of triglyceride mixtures utilizing macroreticular strong acid cation exchange resin adsorbents. The invention herein differs, for example, in utilizing an adsorbent different from that used in Ser. No. 043,394 and advantageous over resin adsorbents from the standpoints of flexibility, cost, and of being inorganic rather than organic in nature.
It is known to remove various non-triglyceride impurities from triglyceride mixtures utilizing various aluminosilicate adsorbents. See, for example: U.S. Pat. Nos. 852,441; 2,288,441; 2,314,621; 2,509,509; 2,557,079. This kind of art discloses using aluminosilicates to decolorize, deodorize, treat used oil, refine, remove trace metals, remove catalyst and remove free fatty acid. The process herein differs, for example, in the feedstock which is essentially free of the type of impurities to which this body of prior art is addressed to removing.
It is known on an analytical scale to separate triglyceride mixtures utilizing silica gel treated with silver nitrate. See, for example, Journal of the American Oil Chemists Society, 41, pp. 403-406 (June 1964). The adsorbent there has the disadvantage of having a short life cycle in that the silver nitrate being not chemically attached is leached out. The adsorbent used herein has no such leaching problem.
U.S. Pat. No. 2,197,861 suggests the possibility of utilizing an aluminosilicate to cause polymerization in an animal, vegetable or marine oil whereby unpolymerized material is readily separated from polymerized material. Such a process would have the disadvantage of producing unuseful polymerized material. The process of the instant invention is carried out without significant polymerization occurring.
Neuzil et al U.S. Pat. No. 4,048,205 and Neuzil et al U.S. Pat. No. 4,049,688 and Logan et al U.S. Pat. No. 4,210,594 disclose the fractionation of alkyl fatty carboxylate mixtures using synthetic crystalline aluminosilicates (zeolites). These crystalline aluminosilicate adsorbents typically contain up to about 25% amorphous aluminosilicate, e.g., clay. The process of the invention herein differs, for example, in the feedstock. The process of the invention herein also differs in the adsorbent which is advantageous over the crystalline zeolite adsorbents from the standpoints of versatility (in that, with the adsorbent herein, the same equipment and packing is advantageously used for separation of alkyl carboxylates and triglycerides--this is not true for crystalline zeolites), flexibility (in that silicon to aluminum ratio and surface area are readily selected for the adsorbent herein--this is not true for crystalline zeolites), and dynamic capacity (in respect to selectively adsorbing triglyceride of higher Iodine Value).
Lam et al, "Silver Loaded Aluminosilicate As a Stationary Phase for the Liquid Chromatographic Separation of Unsaturated Compounds," J. Chromatog. Sci. 15 (7), 234-8 (1977) discloses the analytical (chromatographic) separation of bromophenacyl carboxylates on the basis of unsaturation utilizing silvered, surface aluminated silica gel adsorbents of microparticulate particle size (which particle size is not readily handled in a non-analytical commercial context and can result in significant loss due to suspension of particles in solvent). The process of the instant invention differs at least in the feedstock and in the adsorbent chemical structure and in the adsorbent particle size.
Breck, D. W., Zeolite Molecular Sieves, John Wiley & Sons, New York, 1974, pages 11-13 generally describes synthetic amorphous aluminosilicates (permutites) and uses thereof. The adsorbent herein is particular permutite as described in detail below.